chore: rebrand to Agent Orchestrator + fix pragma busy_timeout crash

Rebrand all user-visible BTerminal references to Agent Orchestrator
(window title, product name, identifier, status bar, updater URL,
context registration, CLAUDE.md branch reference).

Fix critical btmsg/bttask crash: pragma_update uses execute() internally
but PRAGMA busy_timeout returns a result row, causing "Execute returned
results" error that silently broke all CommsTab message loading.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

v2/src-tauri/src/bttask.rs

@@ -33,7 +33,7 @@ fn open_db() -> Result<Connection, String> {
         .map_err(|e| format!("Failed to open btmsg.db: {e}"))?;
     conn.query_row("PRAGMA journal_mode=WAL", [], |_| Ok(()))
         .map_err(|e| format!("Failed to set WAL mode: {e}"))?;
-    conn.pragma_update(None, "busy_timeout", 5000)
+    conn.query_row("PRAGMA busy_timeout = 5000", [], |_| Ok(()))
         .map_err(|e| format!("Failed to set busy_timeout: {e}"))?;
 
     // Migration: add version column if missing